Mosquito-borne diseases such as; malaria, zika virus and dengue fever are growing health concerns, affecting the health of millions of people annually. These mosquitoes have been majorly controlled through the use of insecticides over the years. However, there is a rising concern and increasing evidence which suggests that mosquito populations are building resistance to these insecticides, thereby making them less effective in the control of these diseases.
In efforts to address this worrisome and dangerous turn, NAVRC through the effort of the Disease Surveillance and Epidemiological Response Section (DSERS); is conducting study, to determine changes in susceptibility status of Aedes and Anopheles mosquitoes to the four major classes of insecticides approved by WHO. This study is being carried out in the three LGAs within Enugu metropolis. The study will help to collate valuable information on mosquito populations, specie abundance, and resistance patterns. This will help in the development of more effective mosquito control measures, in order to combat these dangerous diseases that are being transmitted by mosquitoes.
Preparation for setting of CDC/UV light traps for adult mosquito collections
The study will also help to :determine the species composition of Anopheles and Aedes mosquitoes, their susceptibility status and the resistance mechanisms exhibited by the mosquitoes in the 3 selected LGAs.
In addition, it will help to detect the sporozite rates in Anopheles mosquitoes; and also to determine the parity by dissection of 20% of Anopheles mosquitoes collected in the selected study areas.
Entomologist carrying out larval sampling in domestic containers
The study areas are location in the 3 LGAs that make up Enugu Urban.
Iva Valley- Enugu North
Abakpa Nike- Enugu East
Akwuke Layout- Enugu South
This selection took into account several factors which included: human population density, pre water bodies, high and low density areas, as well as areas with clusters of vegetation.
METHODOLOGY:
Ovitrapping method will be used to sample for Aedes mosquitoes that are domestic and peri domestic container breeders. The eggs collected will be will be hatched and reared to adult stage and determine their susceptibility to insecticides. Resistance status will also be determined using molecular methods/analysis. Larval sampling method are used to collect immature stages of both Aedes and Anopheles . The collected larvae will be reared to adult stage to identify and determine their resistance status.
The CDC Light/UV traps are used for the adult collecting of mosquitoes due to their attraction to light. While the CDC light traps are set indoors for the collection of adult mosquitoes that are indoor biters, the CDC/UV light traps are set outdoor for collection of adult mosquitoes which are outdoor biters . The collections are done hourly and lasts from 6.pm to 6.am each day. The Pyrethroid Spray Catch (PSC) is employed for the collection of indoor biters resting mosquitoes species.
Pyrethroid Spray Catch for indoor resting mosquito collections
Setting of CDC light traps for collection of endophagic adult mosquitoes
CDC/UV Light trap for collection of exophagic adult mosquitoes
Inspection of ovitrap ribbons for positive eggs
following the field collections, non blood-fed female mosquitoes of the two genera that are 2-5 days post emergence will be subjected to susceptibility tests according to WHO protocol (WHO,2013). About 20% mosquitoes collected will be dissected to determine their parity level.
NAVRC officers in the field carrying out the study
